IMMUNOHISTOCHEMICAL STUDY OF CONSTITUENTS OTHER THAN BETA-PROTEIN IN CANINE SENILE PLAQUES AND CEREBRAL AMYLOID ANGIOPATHY

To clarify the significance of the constituents of canine senile plaqu es (SPs) or cerebrovascular amyloid deposits, paraffin and cryostat, s ections of canine brains were examined by immunohistochemistry using a ntibodies against cathepsin B (CB), cathepsin D (CD), cystatin C (CC), alpha-1-antichymotrypsin (ACT), heat shock protein 70 (HSP70), ubiqui tin (Ubq), and apolipoprotein E (Apo E). On the cryostat sections, all types of canine SPs and cerebrovascular amyloid deposits in both arte rioles and capillaries were positive for Apo E. On paraffin sections, the Apo E immunoreactivity of diffuse plaques was weak and varied acco rding to the method of fixation or pretreatment before immunostaining. Moreover, amyloid plaques were found to contain several elements that were positive for CC, ACT, CD, and Ubq, and a subset of vascular amyl oid deposits around cortical capillaries showed significant immunoreac tivity for CD, CC, and ACT. In addition, vascular amyloid deposits in the arterioles showed moderate CD immunoreactivity and were intensely Apo E positive. No significant labeling of canine SPs or vascular amyl oid deposits was detected when the antibodies against CB and HSP 70 we re applied to the cryostat and paraffin sections. These results indica ted that, of the constituents examined, Apo E might be most closely re lated to canine beta-amyloidosis in the early stage of this brain diso rder.